Month: January 2013
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There are several intelligence studies for Cubans, including at least two Raven standardizations, some international assessment data, and a few different test measures for Cuban Americans. The message of all these test results is complicated and leaves us with a few puzzles.

IQ and the Wealth of Nations (2002) and IQ and Global Inequality (2006) both list one intelligence study for Cuba: a large Standard Progressive Matrices standardization (Alonso Garcia, 1973 ). In another anomaly, however, this reference has disappeared from the latest version of the dataset (Lynn & Vanhanen, 2012). Cuba is missing from their list of ‘National IQs’ (p. 391), and the reference is not in the bibliography. But this omission is clearly a mistake, since one table (p. 22) still features a ‘Measured IQ’ score for Cuba—85—the same score paired with this study in the previous books. Continue reading

Skin color is a (very imperfect) proxy for white ancestry in African Americans and Hispanics. If racial and ethnic gaps in intelligence have a genetic component, we would expect lighter skinned individuals to have higher IQs, on the average. Further, because g is the main heritable component of intelligence, tests with higher g loadings should show larger associations with skin color.

We investigated these hypotheses in the NLSY97 sample. It contains interviewer reports on facial skin tone of the respondents as measured on a scale of 1 (lightest) to 10 (darkest). The interviewers used a “color card” as a reference.

All the correlations below are significant at conventional levels unless otherwise indicated. Because of the way skin color is coded in this analysis, negative correlations between skin color and test performance are expected if the hereditarian hypothesis is correct.

I found that among blacks, the correlation between g scores and skin color (darkness) was -0.133 (N=1856), whereas T scores were unrelated to skin color (r=-0.012, ns; N=1856). Among Hispanics, g scores correlated with skin darkness at -0.123 (N=1051), while T scores were unrelated to skin color (r=0.062, ns; N=1051). Therefore the results are about as expected. (See the previous post for information about the T factor.)

Applying again the method of correlated vectors (MCV), we found that vectors of skin color-test gap correlations were strongly and significantly associated with g loadings within populations. In other words, lighter-skinned individuals tended to outscore darker-skinned coracials/coethnics more on tests with higher g loadings. Among blacks, the correlations were r=-0.84 and rho=-0.75, and among Hispanics r=-0.60 and rho=-0.59 (correcting for unreliability would make all these correlations somewhat stronger).

The MCV results could be interpreted in terms of genetic effects: tests with higher g loadings are more heritable, and skin color is a proxy for white ancestry and thus presumably better “IQ genes”. But why would these within-population color analyses produce the expected correlations between g loadings and race markers (i.e., skin tone) when the between-population MCV analysis, presented in the previous post, did not? It appears that on the ASVAB g is the major source of racial/ethnic differences, but the T factor also contributes to the gaps. (Cohen’s d’s on the g scale were B-W 1.124, B-H 0.368, and H-W 0.759, while on the T scale they were B-W 0.561, B-H 0.261, and H-W 0.306.) However, T is not associated with skin color within populations, which suggests that its heritability is low and it is linked to race and ethnicity for non-genetic reasons. This would explain why the MCV results from within- and between-population analyses differ.

In the NLSY97, higher g is associated with lighter skin among blacks and Hispanics. This is in accord with hereditarian theory, but nurturists would of course argue that these correlations are due to colorism. These competing hypotheses could be tested by comparing skin color-IQ associations within and between families, as was done here.

A long-time reader and an occasional commenter (under various pseudonyms) in the “Steveosphere”, I’m making my debut as a blogger on these topics. My intention is to post both empirical analyses and more general pieces touching on human biodiversity.

My professional background is not in psychometrics, genetics, or anything related. However, I believe that diligent amateurs can break new ground on these topics, as exemplified by John Fuerst’s work at Occidental Ascent. While HBD is thriving in academia in the form of research programs on individual differences, research on race differences is moribund. Amateurs will have to pick up the slack.

Others have remarked that they cannot entirely disentangle their interest in HBD from their political views. This applies to me, too, and I think, probably naively, that hard-hitting discoveries in HBD could mitigate some of the more negative trends in Western society. But more on that later, perhaps.

According to Spearman’s hypothesis, black-white gaps on cognitive tests are larger on tests that are better measures of g, or general mental ability. If g is the only or main source of the black-white gap, it indicates that within- and between-race differences are qualitatively similar and that understanding the nature of the racial gap requires that we understand the nature of g.

One of the ways that the late Arthur Jensen used to test the hypothesis was the method of correlated vectors (MCV). It involves factor analyzing a battery of cognitive tests taken by a sample of individuals from different races, and correlating the resultant vector of g loadings with the magnitudes of racial differences on each subtest of the battery. The expectation is that tests with higher g loadings are associated with larger racial gaps. Jensen did a number of analyses of this kind, and found that the average correlation between g loadings and subtest differences across many different samples of blacks and whites was 0.63 (after correction for unreliability), supporting the notion that g is the main source of the black-white gap. Analyses of Hispanic-white gaps have also generally supported the idea that g is their major source.

John Fuerst and I studied Spearman’s hypothesis in the NLSY97 sample. The sample sizes in the NLSY97 are ~4400 for whites, ~2300 for blacks, and ~1800 for Hispanics, although they may be lower in specific analyses below. We mostly followed the procedures in Nyborg & Jensen 2000, although we used principal axis factoring rather than PCA. The NLSY97 participants took the ASVAB, which comprises the following tests:

The ASVAB yielded a similar two-factor structure across the black, white, and Hispanic samples. The first factor, which we identified as g, explains about 60 percent of the variance in the ASVAB, while the second factor explains about 10 percent; the rest can be regarded as test-specific variance and measurement error. The second factor is not very easily interpretable, but I would tentatively consider it as representing technical knowledge because it has some of its highest loadings on the Auto and Shop Information tests, which have questions like this:

A fuel-injected engine does not need:

(A) spark plugs(B) a fuel pump(C) a carburetor(D) an alternator

The ASVAB is the Armed Services Vocational Aptitude Battery, so it contains also items that would not show up in a typical IQ test. I’ll call the second factor the T factor.

We correlated the averaged g loadings of each race/ethnicity pair with the magnitudes of white-black, black-Hispanic, and white-Hispanic gaps on each ASVAB test. All the Pearson’s r and Spearman’s rho analyses showed small to moderate positive correlations, none of which were statistically significant at conventional levels (significance testing is based on Spearman’s rho in these analyses, see Nyborg & Jensen 2000 for details). For example, here’s the scatter plot from the black-white analysis:

However, it could be that the expected correlations aren’t there because of confounding due to different reliabilities of the tests. However, controlling for reliabilities doesn’t substantially change the results (not shown here).

Therefore, the MCV does not support the hypothesis that g is driving the racial/ethnic differences in the ASVAB tests. So what then explains the fact that gaps differ across tests? I correlated the loadings of the second factor, the T factor, with differences in test means between whites, blacks, and Hispanics. Surprisingly, the T factor is strongly (r=0.75, rho=0.72) and highly significantly (p<0.01) correlated with the magnitudes of the gaps in the black-white analysis. The results hold even when partialling out reliabilities. The scatter plot looks like this:

In the black-Hispanic and Hispanic-white analyses the results are broadly similar, although the correlations are somewhat smaller and not always significant. Thus the racial/ethnic gaps are not only not explained by differences in g loadings, but are in fact explained by loadings on the T factor which is uncorrelated with g! Does this mean that T and not g is the main source of racial/ethnic differences in ASVAB abilities? In fact, it does not indicate that, and these analyses only demonstrate the shortcomings of the MCV.

One way of studying how different factors contribute to differences between the mean scores of races/ethnicities is to do a point biserial correlation between each racial/ethnic dichotomy and scores on each test and partial out factor scores on either factor. Here’s the results from the black-white analysis (all the results below are significantly different from zero unless otherwise indicated):

Zero-order

g partialled out

T partialled out

GS

0.358

0.052

0.337

AR

0.339

.003 ns

0.377

WK

0.321

.002 ns

0.322

PC

0.284

-0.083

0.317

NO

0.130

-0.143

0.261

CS

0.170

-0.060

0.275

AI

0.295

0.111

0.217

SI

0.368

0.188

0.317

MK

0.279

-0.067

0.357

MC

0.378

0.111

0.350

EI

0.289

-.006 ns

0.249

AO

0.297

0.034

0.315

As can be seen, partialling out g scores removes most of the gaps in all tests, while partialling out T scores has only a small effect. Thus g is the main source of cognitive differences between blacks and whites, while T is a minor source. For some reason, T is nevertheless a major source of differences between the relative sizes of gaps on different tests, which is why the MCV analysis fails.

The results from Hispanic-white analyses are rather similar:

Zero-order

g partialled out

T partialled out

GS

0.262

0.068

0.238

AR

0.198

-0.054

0.212

WK

0.236

0.036

0.222

PC

0.179

-0.069

0.188

NO

0.139

-0.020

0.207

CS

0.105

-0.045

0.162

AI

0.19

0.068

0.148

SI

0.248

0.106

0.206

MK

0.175

-0.056

0.214

MC

0.211

-0.002 ns

0.181

EI

0.216

0.026

0.179

AO

0.097

-0.101

0.114

Finally, black-Hispanic differences:

Zero-order

g partialled out

T partialled out

GS

0.102

-0.012

0.122

AR

0.167

0.081

0.224

WK

0.09

-0.032

0.121

PC

0.12

-0.004 ns

0.163

NO

-0.028

-0.162

0.075

CS

0.072

-0.027

0.147

AI

0.127

0.060

0.105

SI

0.14

0.117

0.159

MK

0.117

-0.018

0.189

MC

0.208

0.168

0.229

EI

0.073

-0.024

0.100

AO

0.256

0.192

0.272

Overall, these results support the hypothesis that g is the major source of racial/ethnic differences in the ASVAB, particularly between whites and blacks. The analysis also shows that the MCV is a flawed method, which is of course well known. For example, according to Ashton and Lee 2005, “first, associations of a variable with non-g sources of variance can produce a vector correlation of zero even when the variable is strongly associated with g; second, the g-loadings of subtests are highly sensitive to the nature of the other subtests in a battery, and a biased sample of subtests can cause a spurious correlation between the vectors.”

Multi-group confirmatory factor analysis appears to be a much better method for testing Spearman’s hypothesis. At the moment, that method is unfortunately beyond my skills and patience.

In part 2 of this post I’m going to extend this analysis to differences in skin color.

See here for John’s SPSS syntax for combining the ASVAB variables (there are two of them for each test), regressing out the effect of age on ASVAB scores, and performing a factor analysis on the ASVAB.

Greetings! I’m one of the editors of the HBD Bibliography. I became interested in HBD about five years ago, began to read widely in the field, and started to maintain a bibliography of things I had read (a habit from grad school). I shared this bibliography with others, and we decided to put it on line so others could benefit from it. I do not claim to be an expert on HBD; the bibliography is part of my learning experience as well. After we had put the bibliography online, we received many emails from people suggesting materials, so the bibliography has grown at least tenfold in size. While we don’t agree with every book or article on the bibliography, we put them out there so others could benefit from them. There are hyperlinks for all the books, articles and blog posts on the reading list. Many of the journal articles and books have hyperlinks to free PDFs on various websites. If you can think of anything that should be added or corrections that should be made, please email them to hbdbibliography@gmail.com. Please also email new articles, blog posts and books. We’ll typically tweet blog posts (to our 2,500 followers), and tweet and add to the bibliography books and articles. (We’re trying to cut back on adding blog posts to the bibliography, unless they’re exceptional.) I hope you enjoy. Please share the bibliography with friends and colleagues.

Lynn’s international dataset lacks data for Haiti. The Global Bell Curve (2008) simply reports “Nothing is known of the intelligence of the population of Haiti” (p. 147). IQ and the Wealth of Nations (2002) estimates an IQ of 72 by regional comparison with Jamaica. IQ and Global Inequality (2006) estimates an IQ of 67 by comparison with Jamaica, St. Lucia, and Dominica. This is the estimated value still reported in Intelligence (2012).

Figure 1 below shows the last five years of SAT scores for African Americans who were a part of the Department of Defense educational system (DoDEA) and for those who were not (Nation). The former, the children of enlisted personal, perform almost 0.3 standardized units better than the latter. Elsewhere, I have documented that this 0.3 difference can be found in DoD schools both in the US and abroad.

An obvious explanation for the DoDEA/ Nation difference is parental selectivity. Entrance into the military is mostly limited to those with AFQT z-scores above -1 relative to a US national mean of 0. As the Black cognitive ability mean is about -1, on the same scale, only the upper half of the Black population is qualified for entrance into the military; as a result, Africa American recruits represent, on average, the 75th percentile of the Black cognitive ability distribution. As such, those selected should be about 0.67 SD (standardized units) above the African-American mean. Given the coefficient of assortative mating typically reported in the literature of 0.33, and assuming a trivial number of Military-Military parings, a random pair of African Americans, for which one individual is or was a member of the military, should have a mid parent IQ 0.45 SD above that of a random pair for which neither individual is or was a member of the military. Multiplying by the typically found coefficient of regression of 0.6 gives one a military, non-military offspring difference of about 0.27 – and this would account for the DoDEA/Nation difference in full. In theory. Continue reading

I don’t know where to begin. If I have to introduce myself I could say that I’m chinese, that my english is awful, that no one knows who I am, and that the average reader of this blog is probably much older than me. Also, it is clear that Jason Malloy and John Fuerst have followed the IQ-race debate for many years now and I am not as knowledgeable as they are – far from it – but knowledgeable enough to write this. To be honest, around two years ago I didn’t even know that blacks have a lower cognitive ability than any other races, as assessed by IQ tests, until I came across this paper “Thirty Years of Research on Race Differences in Cognitive Ability” – in February/March 2011 if I remember correctly. This has caused a stir in my mind, and struck my curiosity. Since that day, I wanted to be better informed, collecting information and data that either reject or confirm the theory posited by the hereditarians. Gradually I was moving to the dark side. You could say I am a hereditarian now.

Among all the books and papers I have read so far, I would highly recommend Arthur Jensen (e.g., The g Factor, Educability & Group Differences, Bias in Mental Testing). I think he is the one who has made the most devastating criticisms against the environmental-cultural hypothesis, and James Flynn being the toughest opponent of the hereditarian side. I am not particularly interested in the consequences of the victory of one side over the other, but if I have to say a word about my political view, which is not worth discussing, the only thing I would say is that no one (and even asians – at least those who live in western countries) would agree with me. I indeed see all the advantages of an ethnically homogeneous country, regardless of the tenability of the “race realism” thesis, which has become my new obsession. My goal in joining this blog is to pursue what I was constantly trying to succeed in for these two last years : refuting the race realism case. And I have not yet succeeded.

Richard Lynn’s international intelligence dataset has proved useful to many different researchers. (For example, in the year 2012 it was used by Hafer, Jones, Kalonda-Kanyama, Rindermann, Woodley.) His dataset has also been criticized over its accuracy and thoroughness. Although this data has been elaborated and corrected over time, some errors have been persistent. For example, IQ & the Wealth of Nations (2002) reported an IQ of 59 for Equatorial Guinea, based on a small study by Fernández-Ballesteros et al. (1997). Lynn subsequently emphasized this as the lowest national score in the dataset (Lynn & Vanhanen 2006, pp. 1-2), and this peculiarity, paired with a meager sample size (N=48), made it an easy target for critical reviewers already discomfited by the low values for Africa in general (Barnett & Williams 2004; Berhanu 2007). However, only veteran anti-hereditarian, Leon Kamin, bothered to eventually check the reference, and indeed, he found a major error: the sample was taken from a school for mentally handicapped children. But even Kamin’s reading was inadequate, and the full extent of the error wasn’t reported until Wicherts et al. (2010): Continue reading

What happens if the Black-White IQ difference is entirely environmental in origin ? I argue here that we cannot be certain that the gap will disappear, and it is even possible that the gap would have increased if the between-group heritability (BGH) of IQ was lower than what it actually is.

Insofar as the socio-economic status (SES) is an index of cognitive stimulation, through wealth, culture, life style, parental expectations, parenting, and so on, it would be useful to examine the magnitude of the IQ gap at different levels of SES.Continue reading